The entry of intake air into an outboard engine is performed through an intake duct which is provided at an upper portion of the rear end of a cowling. Water spray splashed up in the course of navigation may enter the intake duct together with the entering intake air. The water spray is entrained by the intake air into the engine or onto the electric equipments of the engine thereby to cause engine troubles. In order to solve this problem, it is effective to provide intake ports in the intake duct at the upper portions of both the right and left walls. Even in such a construction, however, if the displacement of the engine is increased, the vacuum that will be established in the cowling is accordingly raised to a remarkably high level thereby to tend to increase the entry of water into the cowling.
It is, therefore, an object of the present invention to provide an intake duct for an outboard engine, which avoids the aforementioned problem, which prevents much entry of water into the cowling and in which the entry water, if any, is unlikely to wet the engine or its electric equipment or to reach the intake system of the engine.